But how much is it really?
LONG VERSION (Only read if interested why I need this to be answered)
In my car when I start the car the Pumpkin HU goes into shutting down.
The Voltage on the yellow permanent power drops down to 11,4 Volts. I have a very strong battery compared to the engine.
To make sure it doesn't power off because of the car power supply on the yellow wire, I isolated the unit from the car.
powered it with a total isolated 12 Volt battery and put a 12 Volt on the ACC. Than I seperated the 12V from the ACC (keeping the 12V on the yellow)
and still got the shut down.
The ACC during starting the car engine drops down to 0 Volts.
So I'm 100% confident the car unit reboots simply because of the ACC drop.
I can even power the ACC with a 12 Volt battery I hold in my hands.. and the yellow with the car battery, then start the car.. and it doesn't shutdown because the 12Volt battery in my hand is isolated from the car.
So I'm very sure the shut down is simply because during the start of the car the voltage drops at 0Volts and even a small 12V battery can keep the unit running during start the car.
So to handle this, I want to use a capacitor with a resistor and a few diodes to make sure the current flows in the right direction, and the resistor in front of the capacitor of course to avoid 0 Ohm while starting.
This works in theory, but I also want to keep the unit running after I switch off the car. Let's say for another 30 seconds I need 12Volts on the ACC wire to make sure the unit remains on!!
Would a 22000uF capacitor be enough? At 12 volts minus 0,55 Volts on the Diode and assume the car radio switching off below 9,5 Volts I'd have 12 Volts - 9,5 minus 0,55 = roughly 2 Volts. 0,022F * 2 Volts = 0,044Coulomb = A * s..
so if A is 1mA it would be enough for 0,044/0,001 = 44 seconds but if it's 0,1mA on ACC it's enough for 440 seconds but if it's 10mA it would be only 4,4 seconds.
So how much is really drawn over the ACC if the unit is powered by the yellow line?
Basically I could do this math myself if I know how much the inner resistor value is on the Pumpkin HU on the ACC?
If it's 500 Ohms it would be 24mA but if the inner resistor on the red signal wire is 5kOhm we're talking 2,4mA or if you use a 50kOhm it would be 0,24mA.Statistics: Posted by mrgenie — Fri Apr 21, 2017 8:25 pm
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